/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.schemas.utils;



import com.bff.gaia.unified.sdk.schemas.Schema;

import com.bff.gaia.unified.sdk.schemas.annotations.SchemaCreate;

import com.bff.gaia.unified.vendor.guava.com.google.common.collect.Lists;

import com.bff.gaia.unified.vendor.guava.com.google.common.collect.Maps;



import javax.annotation.Nullable;

import java.lang.reflect.Constructor;

import java.lang.reflect.Field;

import java.lang.reflect.Method;

import java.lang.reflect.Modifier;

import java.security.InvalidParameterException;

import java.util.*;

import java.util.stream.Collectors;



import static com.bff.gaia.unified.vendor.guava.com.google.common.base.Preconditions.checkArgument;



/** A set of reflection helper methods. */

public class ReflectUtils {

  static class ClassWithSchema {

    private final Class clazz;

    private final Schema schema;



    ClassWithSchema(Class clazz, Schema schema) {

      this.clazz = clazz;

      this.schema = schema;

    }



    @Override

    public boolean equals(Object o) {

      if (this == o) {

        return true;

      }

      if (o == null || getClass() != o.getClass()) {

        return false;

      }

      ClassWithSchema that = (ClassWithSchema) o;

      return Objects.equals(clazz, that.clazz) && Objects.equals(schema, that.schema);

    }



    @Override

    public int hashCode() {

      return Objects.hash(clazz, schema);

    }

  }



  private static final Map<Class, List<Method>> DECLARED_METHODS = Maps.newHashMap();

  private static final Map<Class, Method> ANNOTATED_CONSTRUCTORS = Maps.newHashMap();

  private static final Map<Class, List<Field>> DECLARED_FIELDS = Maps.newHashMap();



  /**

   * Returns the list of non private/protected, non-static methods in the class, caching the

   * results.

   */

  public static List<Method> getMethods(Class clazz) {

    return DECLARED_METHODS.computeIfAbsent(

        clazz,

        c -> {

          return Arrays.stream(c.getDeclaredMethods())

              .filter(m -> !Modifier.isPrivate(m.getModifiers()))

              .filter(m -> !Modifier.isProtected(m.getModifiers()))

              .filter(m -> !Modifier.isStatic(m.getModifiers()))

              .collect(Collectors.toList());

        });

  }



  @Nullable

  public static Constructor getAnnotatedConstructor(Class clazz) {

    return Arrays.stream(clazz.getDeclaredConstructors())

        .filter(m -> !Modifier.isPrivate(m.getModifiers()))

        .filter(m -> !Modifier.isProtected(m.getModifiers()))

        .filter(m -> m.getAnnotation(SchemaCreate.class) != null)

        .findFirst()

        .orElse(null);

  }



  @Nullable

  public static Method getAnnotatedCreateMethod(Class clazz) {

    return ANNOTATED_CONSTRUCTORS.computeIfAbsent(

        clazz,

        c -> {

          Method method =

              Arrays.stream(clazz.getDeclaredMethods())

                  .filter(m -> !Modifier.isPrivate(m.getModifiers()))

                  .filter(m -> !Modifier.isProtected(m.getModifiers()))

                  .filter(m -> Modifier.isStatic(m.getModifiers()))

                  .filter(m -> m.getAnnotation(SchemaCreate.class) != null)

                  .findFirst()

                  .orElse(null);

          if (method != null && !clazz.isAssignableFrom(method.getReturnType())) {

            throw new InvalidParameterException(

                "A method marked with SchemaCreate in class "

                    + clazz

                    + " does not return a type assignable to "

                    + clazz);

          }

          return method;

        });

  }



  // Get all public, non-static, non-transient fields.

  public static List<Field> getFields(Class<?> clazz) {

    return DECLARED_FIELDS.computeIfAbsent(

        clazz,

        c -> {

          Map<String, Field> types = new LinkedHashMap<>();

          do {

            if (c.getPackage() != null && c.getPackage().getName().startsWith("java.")) {

              break; // skip java built-in classes

            }

            for (Field field : c.getDeclaredFields()) {

              if ((field.getModifiers() & (Modifier.TRANSIENT | Modifier.STATIC)) == 0) {

                if ((field.getModifiers() & (Modifier.PRIVATE | Modifier.PROTECTED)) == 0) {

                  checkArgument(

                      types.put(field.getName(), field) == null,

                      c.getSimpleName() + " contains two fields named: " + field);

                }

              }

            }

            c = c.getSuperclass();

          } while (c != null);

          return Lists.newArrayList(types.values());

        });

  }



  public static boolean isGetter(Method method) {

    if (Void.TYPE.equals(method.getReturnType())) {

      return false;

    }

    if (method.getName().startsWith("get") && method.getName().length() > 3) {

      return true;

    }

    return (method.getName().startsWith("is")

        && method.getName().length() > 2

        && method.getParameterCount() == 0

        && (Boolean.TYPE.equals(method.getReturnType())

            || Boolean.class.equals(method.getReturnType())));

  }



  public static boolean isSetter(Method method) {

    return method.getParameterCount() == 1 && method.getName().startsWith("set");

  }



  public static String stripPrefix(String methodName, String prefix) {

    if (!methodName.startsWith(prefix)) {

      return methodName;

    }

    String firstLetter = methodName.substring(prefix.length(), prefix.length() + 1).toLowerCase();



    return (methodName.length() == prefix.length() + 1)

        ? firstLetter

        : (firstLetter + methodName.substring(prefix.length() + 1, methodName.length()));

  }



  public static String stripGetterPrefix(String method) {

    if (method.startsWith("get")) {

      return stripPrefix(method, "get");

    }

    return stripPrefix(method, "is");

  }



  public static String stripSetterPrefix(String method) {

    return stripPrefix(method, "set");

  }

}